Adele, Mumford & Sons and Laura Marling cut their teeth in the rock clubs of West London, and Treetop Flyers spent a few pint-soaked nights supporting these meteoric talents long before they became Shepherd’s Bush rock fixtures themselves. This scene — which revolved around Communion, the collective and label co-founded by Mumford & Sons’ Ben Lovett — encouraged the relentlessly gigging musicians to form the twang-loving quintet in 2009 while they witnessed the rise of their rock compatriots. Now, Treetop Flyers are heading stateside with their full-length debut on Partisan, “The Mountain Moves,” and lead singer Reid Morrison is quick to defend its flawless instrumentation and confessional tendencies as more than a jangly, boot-stomping fad. “We’ve liked American folk music since we were little kids — Doc Watson, Jackson Browne, Crosby Stills Nash & Young — so it’s not like we’re playing this way because it’s an ‘in’ sound,” he says. For Partisan co-founder/president Ian Wheeler, the band’s drive and live chops make Treetop Flyers an ideal addition to his like-minded roster, which includes Deer Tick and Sallie Ford & the Sound Outside. “They’re at the top of their field as far as songwriting and performing go,” Wheeler says. “This is one of the most genuine bands we’ve come across. They’re willing to do whatever it takes to make a living making art, and that’s always a big thing for us. That’s something we saw early on and wanted to support as long as we possibly can.”